The invention relates to an apparatus for testing the tooth flanks of gearing, e.g. gear wheels or gear segments, having involute toothing.
Such testing apparatus is known comprising a rolling generating cylinder which is connected to the test gear and on which a straight-edge is arranged to roll without slip to produce a generating motion, a sensor with a recording device being mounted, together with a guide track which in accordance with the helix angle of the gear is adjustable obliquely of the axis of the gear, on a slide which is displaceable parallel to the axis of the gear under test, said slide itself being supported on a rolling slide to be displaceable parallel to the straight-edge, the apparatus further comprising a lever with a longitudinal guideway and a pivot connection adjacent the rolling cylinder, said connection having an axis parallel to said rolling cylinder, the lever having further pivot connections with the rolling straight-edge and with an auxiliary slide the lever being longitudinally located by one of the pivot connections but the other of the pivot connections being slidable longitudinally of the lever an engagement element slideable in said guide track being mounted on said auxiliary slide and said gear axis being adjustably locatable relative to said rolling and auxiliary slides for a continuously variable ratio transmission of the rolling movement by way of said lever to the rolling slide and to the sensor, said lever interconnecting the auxiliary slide through said pivot connections with the rolling generating cylinder and the rolling straight-edge.
With one example of such apparatus, constructed according to U.S. Pat. No. 2,770,048, the working capacity is in principle restricted by the lever as regards rolling travel and swivelling angle. If the capacity is to be increased beyond a certain size, then the required increase in the dimensions of the apparatus could cause difficulties in operation or even require very costly auxiliary means and also could result in an uneconomical increase of the total weight.
FIG. 1 of the accompanying drawings shows some of the mechanism of the known constructional form of apparatus, including a gauging or measuring slide 2 arranged to be displaceable on a bed or base 1. Rotatably mounted on the bed 1 is a rolling generating cylinder 3 (so referred to throughout this specification although as well known in the art this mechanism element can be of flat disc form and may consist of only a segment of a cylinder). The rolling generating cylinder 3 engages in a slip-free manner with a rolling straight-edge 4, which is mounted for transverse sliding displacement on the bed 1.
A lever 5 is also mounted to be pivotable with and about the same pivot point as the rolling cylinder 3, in this it differs from the apparatus described in the aforesaid prior specification in which the pivotable lever has its equivalent pivot point spaced from the axis of the rolling cylinder, but in other respects FIG. 1 represents an apparatus which is similar in principle and as in that earlier specification, the lever is longitudinally located by a pivot connection, here represented by the pivot point on the cylinder axis for simplicity. A stud or pin 6 fixed on the straight-edge 4 engages, as an additional pivot point, in a longitudinal slot 7 of the lever 5, which is connected to other elements. The space required for the said lever 5 is designed for a maximum lever pivoting angle .phi. of 30.degree. and even then requires awkward recesses 8 to provide the necessary space width B in the measuring slide 2, the figure showing the slide in full lines in its position for a smallest possible test gear wheel and in chain-dotted lines in its position for a largest possible test gear wheel.